Sprinkler systems



Oct. 30, 1956 p. c. SHERBURNE SPRINKLER SYSTEMS 2 Sheets-Snee. 1

Filed; May 1 1953 FIG. I

INVENTOR. PHILIP C. SHERBURNE ATTOR N EY Oct. 30, 1956 p, c. SHERBURNE2,768,696

SPRINKLER SYSTEMS Filed May 1, 1953 2 Sheets-Sheet 2 V INVENTOR. PH ILIP C. SHERBURNE BY ATTORNEY United States Patent SPRINKLER SYSTEMSPhilip C. Sherburne, Rumford, R. L, assignor to Grinneil Corporation,Providence, R. L, a corporation of Delaware Application May 1, 1953,Serial No. 352,441

9 Claims. (11. 169''37) fire extinguishing medium in-the pipes fromentering thcreinto until actuation of the thermally responsive meansassociated with the outlets and deflectors takes place.

The distributing pipes for bringing a fire extinguishing medium such aswater to sprinkler heads areusually arranged in a generally horizontalposition, and if they are kept filled with the said medium at all timesthe installation may be entirely conventional with the sprinkler headsscrewed directly into fittings located along these distributing pipesand extending therefrom in any convenient directions. If, however, thesystem is liable to be subjected at any time to freezing temperatures itis necessary to employ a system of the so-called dry pipe type in whichthe distributing pipes are normally filled with a gas such as air andfrom which the water is excluded until need for it arises, as when afire occurs or when thefsystem is tested. Such a dry pipe system must-beagain restored to its normally dry condition after a test or afteroperation occasioned by a fire by draining off the water. i

This draining operation presents no difiiculties so far as thedistributing pipes themselves are concerned, because those that arehorizontal are properly pitched during installation to assure theircomplete drainage. However, where it is necessary or convenient toconnect sprinkler heads to the distributing pipes so that they dependdownward therefrom, it is not so easy, after a fire or test, to removethe water collected in any unactuated sprinkler heads which are thusdownwardly disposed. It is clear, of course, that where there is need ofa dry pipe system, because it might be subjected to freezingtemperatures, water collected in such pendent sprinkler'heads cannot betolerated. Freezing of water thus collected would render the pendentsprinkler heads inoperative. It is therefore necessary in dry pipesystems either to drain each pendent sprinkler head individually after afire or test, or to provide closure means for keeping the water out ofthese heads until the heads are thermally actuated by a fire occurringin this vicinity.

To avoid the laborious job of removing each pendent sprinkler head todrain it it has been customary to pro- 7 of the more successful of theseearlier devices is a frangible seal which is located at thefirst-mentioned end of the tubular member and which is shattered by therelease of a spring loaded plunger upon thermal actuation of thethermally responsive means associated with the outlet unit.

The distributing pipes of sprinkler systems are usually located at thetop of the enclosure to be protected from fire, and where the goodappearance of the enclosure so demands these pipes and the tubularmembers extending downward therefrom are entirely concealed above theceiling with only the outlet unit projecting therebelow. However, thevertical space above'the ceiling in which the distributing pipes andtubular members must be located is frequently limited, The portion ofvertical space required for the distributing pipes cannot be easilyreduced, because the size of the pipe is determined by otherconsiderations, but I have discovered that the vertical space which isrequired for the tubular members and which is the greater portion of thetotal vertical space occupied may be made very small when the force todrive the plunger is in each case derived from a helical spring of theconical type arranged in a manner that will be more particularlydescribed. I have further discovered a novel arrangement which will alsobe more particularly described for latching a plunger ,so driven.

When the closure means at the pipe end of the tubular member is formedof a frangible material which is intended to be shattered by aspring-actuated plunger this closure means must be capable ofwithstanding those pressures normally encountered in the distributingpipe and at the same time mustbe capable of being completely shatteredby the plunger when the latter is released. Complete shattering isessential so that the fragments of the closure means will pass freelythrough the tubular connection and be expelled from the outlet and notlodge in the connection or outlet to impede the flow therethrough. Ithas been my experience that a large striking force must be exerted bythe plunger to properly shatter a frangible closure means which iscapable of withstanding the pressures normally encountered in thedistributing pipes. To achieve this large striking force a strong springmust be employed to actuate the plunger. 1 have discovered, however,that when the closure means has a novel configuration which will be moreparticularly described hereinafter, the plunger-actuating spring neednot be as strong as heretofore thought necessary to effect a shatteringeven though the closure means is capable of withstanding distributingpipe pressures.

Accordingly, it is one object of my invention to provide in the tubularmember connecting a pendent outlet unit to the distributing pipe of adry-pipe system a helical spring of the conical type for driving theplunger against the frangible closure means, thereby permitting thelocation of the outlet unit very near the distributing pipe, if suchlocation is desired.

Another object is to provide in systems of the kind being considered animproved, simple and inexpensive latching mechanism for holding theplunger at rest against the force of the spring until the thermallyresponsive means associated with the outlet unit is thermally actuatedand for releasing the plungerupon such actuation.

Another object is to provide in systems of the kind being considered animproved frangible closure means.

Additional objects will hereinafter appear.

The best mode in which I have contemplated applying the principles of myinvention is disclosed in the accompanying drawings but these are to bedeemed merely illustrative because it is intended that the patent shallcover by suitable expression in the appended claims whatever features ofpatentable novelty exist in the invention disclosed.

ice

In the drawings:

Fig. l is an elevation of a portion of a sprinkler system embodying myinvention;

Fig. 2 is a vertical section showing a fitting of a horizontaldistributing pipe and a fluid conducting member leading therefrom to anoutlet unit, this and other structure being in accordance with myinvention and the movable parts being shown in their relative positionswhen the system is inactive;

Fig. 3 is a vertical section like Fig. 2, but with the movable partsshown in their relative positions for fire extinguishing discharge;

Figs. 4 and 5 are horizontal sections taken as on lines 4-4 and 55,respectively, of Fig. 2; and

Fig. 6 is a perspective view of the lower end of the plunger used in myimproved system.

Referring to the drawings, and particularly to Fig. 1, there is shown aportion of a sprinkler system employing outlet units 10 located below aceiling 12 represented in cross-section. Above the ceiling a horizontaldistributing pipe 14 is carried by hangers 16 from some convenientstructural support 18. At suitable intervals along the pipe 14 there areprovided fittings 20 from each of which a generally tubular member Aextends downward to an outlet unit 10. This showing in Fig. 1 is typicalof a sprinkler system installed in a location where there is alikelihood that the system or the portion of it above the ceiling 12 maysometime be subjected to freezing temperatures, and accordingly thewater is normally held back from the distributing pipes by some suitableform of valve (not shown). When such a dry-pipe system is tested todetermine if there are any leaks by admitting thereto water underpressure, or after the system has operated to put out a fire, the watercan be drained from the horizontal distributing pipes readily enough bya convenient drain connection such as a pipe 22. However, it would notbe so easy or practical to drain the numerous pendent units 10 and theirassociated tubular members A if they were allowed to fill with water,and consequently l have provided improved means for preventing theentrance of any water into a tubular member A until its respectiveoutlet unit has responded to a fire started in the vicinity thereof.

In Figs. 2 to 5 inclusive are shown the details of the preferredembodiment of my improved means. The sections of the distributing pipe14 are screwed into aligned openings 20a and 20b of the fitting 20 whichhas a third depending outlet 20c. Into this depending outlet 200 thereis screwed a fixed sleeve 24 which preferably extends far enough up intothe fitting 20 to bring its upper end 24a substantially above the bottomlevel of the flow passageway therethrough. Thus when the distributingpipe 14 is filled with water (either for test purposes or for fireextinguishing discharge) and then subsequently drained, no appreciablequantity of water is likely to stand in the fitting above the upper end24a of the sleeve 24 when, for one reason or another, the removal of thewater from the system is incomplete. Although it is not unusual for somesmall amount of water to remain in the upper end of the fixed sleeve 24above the closure means which is located there, and which will be moreparticularly described presently, this is of no concern even if thiswater freezes because the apparatus of my improved structure will breakthrough any such thin ice formation, as will appear.

A cylindrical extension piece 26 is brazed or otherwise secured to thelower end of the sleeve 24 and extends downward therefrom, substantiallyas shown, to a bell-shaped spring housing 28 which has its hollow upperneck portion 28a suitably fastened to the lower end 26a of thisextension piece. As its name implies, the bellshaped spring housing 28flares outward from this neck portion 28a and has a dependingcylindrical skirt 28b with an inside diameter considerably greater thanthat of the extension piece 26. At its lower end and for a short 4distance upward therefrom this spring housing skirt 28b has its insidediameter still further increased, as at 280, to form a shoulder 28b. Acircular base plate 10a integrally formed on the outlet unit 10 isinserted in this lower end of the spring housing skirt 28b until itbears against the shoulder 28d, and this base plate is there held by atapered snap ring 30 which cooperates with an annular groove 28@suitably located on the inside wall of the spring housing skirt.

The outlet unit base plate 10a has extending downward therefrom a shaftportion 1011 which has a central passage of circular cross-sectiontherethrough. This central passage also extends through the base plate10a, and its side walls are preferably tapered slightly as shown. At itslower end the shaft portion 10b widens into a body portion 1011 having acentral recess 102 which extends thereinto from its lower end and joinsthe central passage 100. At the point where the central passage 10copens into this recess 100 the above-mentioned taper in its side wallsis abruptly reversed to form what substantially amounts to a bevel at 10The purpose of this bevel will presently appear.

The sleeve 24, extension piece 26 and spring housing 28 comprise thetubular member A hereinbefore referred to, and within the vertical flowpassage which these elements form from the fitting 20 to the unit 10there is located a hollow cylindrical plunger B. Preferably this plungeris made up of three pieces, an upper tube 32, a lower tube 34 and ashoulder piece 36. The upper tube 32 is vertically disposed so that itslower end 3211 is located in the spring housing 28 and its upper end 32bextends part way up into the sleeve 24. The outside diameter of thistube is small enough so that the tube is capable of free movement withrespect to the elements by which it is enclosed, and the rim 32c of thetop end of the tube lies in a plane which is not perpendicular to thetube axis. The lower tube 34 is also vertically disposed and has itsupper end 34a brazed or otherwise suitably secured to the bottom end 32aof the tube 32, substantially as shown. This lower tube 34 has anoutside diameter only slightly smaller than the diameter of the upperend of the tapered central passage 10c in the outlet unit 10, and deeplongitudinal slots 34b are formed in this tube from the bottom thereofto provide a plurality of depending flexible segments 340 (see Fig. 6).Because each of these segments may be deflected inwardly toward the axisof the tube 34 they may be inserted down through the tapered centralpassage 10c, as illustrated, until the outwardly bent tip 34d on eachsprings out and lies against the beveled surface 10f at the bottom endof this central passage. The shoulder piece 36 is preferably an annularring which fits nicely around the lower tube 34 and is located thereonso that its upper side is abutted against and welded to the bottom rimof upper tube 32. From this last-mentioned weld the upper side ofshoulder piece 36 slopes downward at an angle which is substantially thesame as the angle at which the upper portion of the spring housingflares outwardfrom its hollow neck 28a.

The lower side of the shoulder piece 36 extends radially outward andoverlies the central winding of a helical spring 38 of the compressiontype which, in its unflexed condition, assumes the conical shape shownin Fig. 3. In this unflexed condition only the outside winding rests onthe upper side of the outlet unit base plate 10a.

Referring now particularly to Fig. 2, my improved device is prepared forinstallation, or loaded, by thrusting the plunger downward until theoutwardly bent tips 34d on the segments of the lower tube 34 emerge fromthe outlet unit central passage 10c and snap out to lie against thebevel 10f. Thereupon, these tips are held in these positions and areprevented from being drawn inward and upward by the insertion of ahemispherical cup 40 up into the segmented bottom end of tube 34 and theforcible holding of this cup in this described position. Otherwisestated, the outside rounded surface of the cup 40 prevents the segmenttips 34d from moving inward, as they must before they can clear thebevel 103 and be drawn up the central passage ltlc by the spring 38.

The lower edge of the cup ill is pressed upward by its engagement withthe outside edge of a spring washer 42 whose downwardly extending hollowhub portion is, in turn pressed upward by the engagement of its lowerend with the inside edge of a second spring washer 44. The outside edgeof this latter washer is pressed upward by an annular shoulder on a capmember 46, and a frangible thermally responsive bulb 48 having its lowerend fixed relative to the outlet unit body portion d seats against thiscap member 46 and presses it upward. In this manner the cup 4!} is heldin position to latch the plunger.

The seat provided to hold fixed the lower end of the frangible bulb 48also serves as a deflector St) for the water which discharges from theoutlet unit, and this deflector is secured to the body portion 10d byarms 50a. Suitable holes 10g are provided in this body portion and whenthese arms have been inserted far enough therein to assure that the cup40 is properly held in place the body portion is crimped around theholes 10g to seize the arms.

The length of the lower tube 34 and the location of the shoulder piece36 thereon are such that when this lower tube is latched as abovedescribed the spring 38 is compressed until all of its coils are pressedagainst the base plate ltla. Consequently, the spring, though occupyinga minimum amount of vertical space, has considerable force stored up init and is ready to drive the plunger upward when the latter is released.

For a short distance downward from its upper rim the sleeve 24 has itsinside diameter somewhat increased, as at 24b, to form a shoulder 24c onwhich there is located a sealing ring 52. This sealing ring is ofresilient material, preferably has a circular cross-section and servesas a seat for the edge of a frangible disc 54 which is held thereon by atapered snap ring 56 cooperating with an internal sleeve groove 240..The underside of the frangible disc 54 is substantially convexed asshown, and since this disc must be depressed somewhat and the sealingring 52 squeezed before the snap ring 56 may be set in place, theresilient material of this sealing ring is pushed largely outwardagainst sleeve wall 24b as well as downward against the shoulder 240.Thus by this convex disc shape the prevention of leakage past the disc54 is assured. Later herein other advantages derived from the convexdisc shape will be explained.

Considering now the operation of my improved system, assume first thatnormal conditions prevail, no fire has started and the water is kept outof the distributing pipes 14 and their fittings by a valve (not shown).Under these circumstances the parts are in the positions shown in Fig.2. The frangible bulb 48 is intact, the plunger B is spring loaded downand latched; and the frangible disc 54 seals off the sleeve 24 from thefiow passageway through the fitting 20.

Now assume that a fire breaks out in the vicinity of this device. Thethermally responsive bulb 4S shatters because of the expansion of theheated liquids and gases therein when the air around this bulb reaches apredetermined temperature. Thereupon, the force which was previouslytransferred to the cup 49 and held it in place is removed. The segmenttips 34d, urged inward and upward by the force of spring 38, are thenable to eject the cup 40 downward by their contact on the hemisphericalupper surface thereof, and simultaneously these tips are pulled off thebevel 10 and into the central passage 100. The plunger is thus releasedand driven upward to shatter the frangible disc 54, and communication isestablished between the now-open outlet unit 10 and the fitting 20 (seeFig. 3).

Either by this release of the gas (air) in the pipes 14 (which gas maybe under pressure) or by separate thermally responsive means (not shown)the valve which is holding back the water may be opened, and water isappropriately discharged on the fire. Obviously, those pendent deviceswhich are remote from the fire and do not respond to the heat therefromneed not be replaced or individually drained when the fire isextinguished and the water is drawn from the system.

It should be noted that upward movement of the plunger is arrested andits top end prevented from damaging the fitting 20 by the engagement ofthe sloped shoulder piece 36 against the correspondingly sloped springhousing 28. Likewise it should be understood that the function of thespring washers 42 and 44 is to provide a small amount of resiliency inthe confinement of bulb 48, thus reducing bulb breakage from roughhandling, and to further provide a certain positive spring force whichhelps to eject the cap member 46 when the bulb shatters.

The bottom end of the housing skirt 28a is provided with notches 28] toreceive a special tool (not shown) for screwing the sleeve 24 into andout of the fitting 20. It will be noted that ceiling holes 12a throughwhich the outlet units extend are large enough to pass the springhousing skirt 28a. Consequently, when it is necessary to repair adepending unit or reset it after the extinguishment of a fire in whichit was actuated, a hole cover 58 may be unscrewed from the ceiling 12and the unit taken down through the hole 12a therein by application ofthe special tool referred to. In this manner the depending units aremade readily accessible without the need for disturbing or removing theceiling.

The advantage of employing a helical spring of the conical type to drivethe plunger completely through the frangible closure lies in the factthat the space required between the outlet unit and distributing pipefor accommodating the spring is kept at a minimum. Systems of thegeneral type described herein are least expensive and involved when thesprings employed to drive the plunger are of the coiled type and actdirectly upon the plunger without the benefit of force directionchanging linkage. This being so the axes of such ,coil springs willgenerally coincide with, or be parallel to, the axes of the tubularmembers connecting the outlet units to the distributing pipes. Itfollows that there must be between the outlet unit and the distributingpipe at least enough space to accommodate the spring deflectionnecessary to produce the proper force, and by using my conical-type,helical spring the additional space needed to accommodate the spring,above that required for the spring deflection, may be very small. In mypreferred form, for example, this additional space may be no greaterthan one diameter of the wire from which the spring is made. This isillustrated in Fig. 2 of the drawings.

Because my frangible disc closure means has the convex shapehereinbefore described, that outer portion of it which is adjacent itssupported edge and against which the open end of the cylindrical plungerstrikes is substantially thinner than its center portion. At the sametime however, this outer portion is fully capable of withstanding thestatic pressures normally encountered in the distributing pipes, forthough it is thinner than the center portion, its location near thesupporting member makes it as adequate in its pressure withstandingfunction as the thicker center portion more remote from that member. Itis apparent, therefore, that the force exerted by the spring to drivethe plunger against the discs outer portion and efiect a propershattering is kept at a minimum when my convex disc shape is employed,and as a result less strong springs may be used, with consequentreduction in expense, than have been possible hitherto with frangibledisc closure means of other configurations.

Another advantage of my convex disc shape is that it appears tocontribute to a very complete shattering of the disc material when theplunger strikes it. Thus, it is customary to form this kind of frangibledisc of a glass material which is tempered to provide thereinappreciable internal strains. Such strains increase the ability of thedisc to withstand static pressures and at the same time cause it toshatter into very small pieces when struck a sharp blow, as by theplunger. It appears that many of these shattering pieces are provided anopportunity to escape from the disc more rapidly when the disc surfacefrom which they originate is convex rather than flat.

Though I prefer to employ a frangible disc of the kind described andshown in the drawings, namely, a disc with a convex side which is remotefrom the contents of the distributing pipe, it will be understood thatany frangible disc which is substantially thinner at the outer portionengaged by the plunger than at the center will have the benefits setforth and is within the scope of my invention.

I claim:

1. In a sprinkler system including a fixed distributing pipe, a tubularconnection adapted at one end to be connected with the distributingpipe, a cylindrical plunger having a substantially unobstructedpassageway therethrough and located within said connection and axiallymovable with respect thereto, closure means at said one end of theconnection adapted to be opened by axial movement of said plunger,spring means interposed between the connection and the plunger andencircling the latter for normally urging such axial movement of thesame, said plunger having deformable end portions, said connectionhaving a surface adjacent said end portions when said plunger is in itsretracted position, a thermally responsive means normally holding theplunger deformable end portions against said surface and thereby frommovement by the spring means until a predetermined thermal conditionactuates the thermally responsive means to release the plunger endportions and thus the plunger for spring-urged movement to open theclosure means.

2. In a sprinkler system including a fixed distributing pipe, a tubularconnection adapted to be extended from the pipe, a movable plungerlocated in the connection, a plurality of flexible, longitudinallyextending segments formed in the plunger end which is remote from thepipe, closure means normally closing the pipe end of the connection andadapted to be opened by movement of the plunger toward the pipe, springmeans interposed between the connection and the plunger for moving thelatter toward the pipe, a fixed annular surface on said connection whichsurface is opposite the segment end portions when the plunger ispositioned to deflect the spring means and against which these ends areadapted to lie when the plunger is so positioned, a member adapted tohold the segment end portions against the fixed annular surface whenpressed theretoward to prevent plunger movement, a fixed outlet unitlocated at the extended end of the connection and having thermallyresponsive means for exerting a force to press the member toward thefixed surface until a predetermined thermal condition actuates theresponsive means, said actuation causing removal of the force andpermitting the spring means to draw the segment end portions from thefixed surface.

3. In a sprinkler system including a distributing pipe, a sprinklerassembly comprising a tubular connection adapted to extend from thepipe, a movable plunger located in the connection, spring meansinterposed between the connection and the plunger for moving the latter,closure means normally closing the pipe end of the connection andadapted to be opened by plunger movement caused by the spring means, anoutlet unit at the extended end of the connection and having thermallyresponsive means which hold the plunger and prevent movement t 8 thereofby the spring means until a predetermined thermal condition actuates thethermally responsive means to release the plunger, said closure meansbeing a frangible disc which is supported at its edge adjacent the pipeend of the tubular connection and which is progressively substantiallythicker toward its center.

4. In a sprinkler system including a fixed distributing pipe, asprinkler assembly comprising a fixed tubular connection adapted toextend from the pipe, a movable plunger located in the connection,spring means of the helical, conical type interposed between theconnection and the plunger for moving the latter, closure means normallyclosing the pipe end of the connection and adapted to be opened byplunger movement caused by the spring means, an outlet unit at theextended end of the connection and having thermally responsive meanswhich hold the plunger and prevent movement thereof by the spring meansuntil a predetermined thermal condition actuates the thermallyresponsive means to release the plunger, said helical, conical typespring means having its coils substantially all in one plane when theplunger is held by the thermally responsive means, whereby the spacerequired between the pipe and the unit to accommodate the spring meansis substantially equal to the space provided for the movement of thespring means.

5. In a sprinkler system including a fixed distributing pipe, asprinkler assembly comprising a fixed tubular connection adapted toextend from the pipe, a cylindrical plunger located within theconnection and movable axially with respect thereto, a plurality offlexible, longitudinally extending segments formed in the end of theplunger which is remote from the pipe and having their ends bentlaterally outward, closure means normally closing the pipe end of theconnection and adapted to be opened by movement of the plunger towardthe pipe, spring means interposed between the connection and the plungerfor moving the latter toward the pipe, an outlet unit at the extendedend of the connection having a fixed, laterally extending annularsurface which the bent segment ends are opposite when the plunger ispositioned to deflect the spring means and over which these ends areadapted to lie when the plunger is so positioned, a wedging cup-likemember adapted to enter part way into the segmented end of thecylindrical plunger and hold the segment ends outward against the fixedsurface when pressed theretoward, thermally responsive means associatedwith the unit for exerting a force to press the wedging cup-like membertoward the fixed surface until a predetermined thermal conditionactuates these responsive means, said actuation causing removal of theforce and permitting the spring means to draw the segment ends from thefixed surface to release the plunger.

6. A sprinkler system comprising a distributing pipe carrying a fluidunder pressure, a tubular connection extending therefrom, a movablecylindrical plunger located in the connection, spring means interposedbetween the connection and the plunger for driving the latter, afrangible closure disc normally closing the pipe end of the connectionand adapted to be engaged and shattered by one end of the plunger toopen the pipe end of the connection when the plunger is driven by thespring means, an outlet unit at the extended end of the connection andhaving thermally responsive means which latch the plunger and preventmovement thereof by the spring means until a predetermined thermalcondition actuates the thermally responsive means to release theplunger, the frangible closure disc being supported at its edge adjacentthe pipe end of the tubular connection, the end of cylindrical plungerwhich shatters the closure disc being concentric thereto and being openso that it engages the closure disc at a portion near the supported discedge, and the closure disc being of tempered glass and having the sidefacing the pipe convex and the other face flat, whereby the portion ofthe disc engaged by the plunger is thin and easily shattered and at thesame time capable of withstanding the pressures in the pipe by reason ofits proximity to the supported disc edge.

7. A sprinkler system comprising a fixed distributing pipe, a fixedtubular connection extending therefrom, a movable cylindrical plungerlocated in the connection, a plurality of flexible, longitudinallyextending segments formed in the plunger end which is remote from thepipe and having their ends bent laterally outward, a frangible closuredisc normally closing the pipe end of the connection and adapted to beengaged and shattered by one end of the plunger to open the pipe end ofthe connection when the plunger is moved theretoward, spring means ofthe helical, conical type interposed between the connection and theplunger for moving the latter toward the pipe end of the former, thespring means being deflected when the plunger is in a predeterminedposition, a fixed outlet unit at the extended end of the connectionhaving a discharge opening and a laterally-extending, annular surfacetherearound which the bent segment ends are opposite and over whichthese ends are adapted to lie when the plunger is in the predeterminedposition, a wedging cup-like member adapted to enter part way into thesegmented end of the cylindrical plunger and hold the segment endsoutward against the fixed surface when pressed theretoward, thermallyresponsive means associated with the unit for exerting a force to pressthe cuplike member toward the fixed surface until a predeterminedthermal condition actuates these responsive means, said actuationcausing removal of the force and permitting the spring means to draw thesegment ends from the fixed surface to release the plunger, thefrangible closure disc being supported at its edge adjacent the pipe endof the connection and being progressively substantially thicker from theedge toward the center.

8. A sprinkler system comprising a fixed distributing pipe carrying afluid, a fixed tubular connection extending therefrom, a movablecylindrical plunger concentrically located within the connection andmovable axially, a plurality of flexible, longitudinally extendingsegments formed in the end of the plunger which is remote from the pipeand having their ends bent laterally outward, a frangible closure discnormally closing the pipe end of the connection and adapted to beengaged and shattered 'by one end of the plunger to open the pipe end ofthe connection when the plunger is moved theretoward, spring means ofthe helical, conical type interposed between the connection and theplunger, said spring means being deflected when the plunger is held in apredetermined position and being capable of moving the plunger towardthe pipe end of the connection when the plunger is released, a fixedoutlet unit at the extended end of the connection having a passagethrough which the fluid is discharged from the connection when theclosure disc is pierced and through which the segments extend when theplunger is in its predetermined position, a laterallyextending, annular,beveled surface surrounding the exterior end of the passage whichsurface the bent segment ends are opposite and over which these segmentends are adapted to lie when the plunger is in the predeterminedposition, a wedging cup-like member adapted to enter part way into theexterior end of the passage and hold the segment ends outward againstthe surface when pressed theretowand, thermally responsive meansassociated wit-h the unit for exerting a force to press the cuplikemember toward the surface until a predetermined thermal conditionact-uates these responsive means to cause removal of the force andpermit the spring means to draw the segment ends from the surface torelease the plunger, the frangible closure disc being supported at itsedge adjacent the pipe end of the connection and being progressivelysubstantially thicker from the edge toward the center.

9. A sprinkler system comprising a distributing pipe, a tubularconnection extending therefrom, a tubular, movable plunger locatedWithin the connection and being of slightly smaller size than saidtubular connection, spring means interposed between the connection andthe plunger for moving the latter toward the pipe end of the connection,closure means normally closing the pipe end of the connection andadapted to be opened by plunger movement caused by the spring means, anoutlet unit at the extended end of the connection and having thermallyresponsive means which hold the plunger and prevent movement thereof bythe spring means until a predetermined thermal condition actuates thethermally responsive means to release the plunger, said closure meansbeing a frangible disc which is supported at its edge adjacent the pipeend of the tubular connection and which is progressively substantiallythicker toward its center whereby said plunger when moved engages thethinner, more fragile peripheral portion of said disc.

References Cited in the file of this patent UNITED STATES PATENTS485,519 Wilson Nov. 1, 1892 2,218,857 Roessner Oct. 22, 1940 2,291,813Knight Aug. 4, 1942 2,327,528 Kendall et al Aug. 24, 1943

